Art of die casting



C. M. GREY.

ART OF DIE CASTING.

APPLICATION FILED OCT. 28,1920.

1 $35,292. Patented Nov. 14, 1922.

2 SHEETS-SHEET l- )NVENTOR Char/er /1 /f rey 87% ATTO N rs c. M. GREY.

ART OF DIE CASTING.

APPLICATION'FILED OCT. 28. 1920.

1,485,292. Patented Nov. 14, 1922 V 2 SHEETS-SHEH 2.

I v Clo/e0 (/oreo v- MIl/ENTUR war/ex M r y Patented Nov. 14, 192 2.

- CHARLES M. GREY,- OF EAST ORANGE, NEW JERSEY.

' ART or DIE CASTING.

Application filed October 28, 1920. Serial No, 420,132.

To all whom it may concern:

Be it known that I, CHARLES M; GREY, a citizen of the United States, residing at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements Pertaining to the Art of Die Casting, of which the following is a specification.

This invention relates to the art of die casting and is directed,'more particularly, to a novel method of manipulating the pressure pot to effect the charging thereof with fluid metal, the subsequent discharging of a portion of the metal into a die, and, thereafter, emptying the pot, when desirable, before recharging the same.

More specifically, the invention, in one of its main aspects, embodies the introduction of metal into a tiltable pressure pot by means p of a vacuum. In practice, a pressure pot, preferably having a substantially U-shaped longitudinal cross section, is employed, and, upon tilting the ot, so as to position the same for introducing metal therein, the nose of the pot, i. e., the metal inlet to the pot, is submerged below the surface of the metal, and beneath the surface dross strata, whereupon a vacuum is produced in the pot with the result that the metal is drawn directly into the pot. The desired quantity of metal having been drawn into the pot, the pot is tilted upwardly, but the vacuum therein is turned off, i. e., broken, before the nose of the pot reaches the dross strata. When the vacuum is broken, the pot is vented to the atmosphere with the result that metal is flowing out of the pot while the nose is passing through the surface of the metal, and, particularly, when passing through the dross strata, thereby effectively precluding any dross or surface impurities from entering the pot.

In the preferred manner of practicing the invention, a very much larger quantity of metal is taken .into the pot than is employed inthe subsequent operations of casting, and p before recharging the pot, the surplus metal may be allowed to flow out of the pot into the main bath of molten metal, the out-flow of metal being so arrangedthat it is occurring while the nose of the pot is being submerged into the bath, so that said out-flow-v I I zle D, adapted to cooperate with thedie (noting current precludes the inflow of slag- In operating as above described, several important advantages result, among which may be mentioned the following. A large charge of clean metal is expeditiously drawn into the pot; no dross can enter the pot, thereby assuring the purity of the -metal; there is no accumulation or piling up of metal inthe pot, and, further, the repeated emptying of the pot insures the uniformity of the metal, both in the main bath and in the pot.

The arts of the apparatus employed in practicmg the present method are so coordinated in operation that during the righting, or return of the pot to its upstanding position, the surplus metal introduced into the pot is allowed to flow from the charging opening while such chargingopening is passing thro'ughthe surface strata of the molten met-a1 bath, thereby obviating the slightest tendency of the surface dross to enter the ot.

Features of the invention, other than those adverted to, will be apparent from the hereinafter detailed description and claims, when read in conjunction with the accompanying drawings.

In the accompanying drawings, I have, for the purpose of illustration, shown one, and the preferred, form of apparatus wherein the method constituting the subject mat-- ter of the invention may be'successfully practiced, butI wish it understood that the form of apparatus shoWn is for the purpose of illustration, only, and is not intended to be exclusive of other forms of apparatus by the'pressure pot at difi'erent times, duringgthe operation of the apparatus.

eferring to the drawings, A indicates a melting pot containin a pool or bath of molten metal B, which forms-the source of supply for the pressure pot C. The melting ot A is; usually mounted in a suitable furnace of which it forms a part and is heated externally by any suitable means.

Thepressure pot C may be of any one of several forms, but is here shown as substantially U-shaped in crosssection. The pot is provided at one end with a discharge nozshown) in such manner, as to feedmolten metal fromthe pot into the die, while the other end of the pot is connected, any

suitable manner, preferably by a flexible tube E, to a system or piping by means of which the pot may be vented, pressure applied to the pot, or air exhausted therefrom.

The pot may be supported in any desired manner, but is here shown as pivotally mounted on a hanger F which is, in turn, mounted for sliding movement on two parallel guides, only one of which is shown and is designated G. By this mounting, the pot may be slid on the guides G into casting position with reference to the die and away from casting position with reference thereto, and, because of the pivotal mounting of the pot, it may, while in retracted position, be tilted to submerge the nozzle below the surface of the molten metal bath B, although the normal position of the pot is the upstanding position shown in Figure 1.

In the form of pot shown, the pot is charged through a charging opening 0? in the nozzle, though it may be otherwise charged, if desired.

For the'purpose of illustration, I have shown means for tilting the pot embodying a crank H, which is rigid with respect to the pot and is adapted when the pot is retracted to engage with either a fixed or movable member it, so that as the pot is retracted, the

'. crank H and member It will engage with one another and effect the tilting of the pot.

The piping system hereinbefore referred to as connected with the pressure pot C through the flexible tube E may differ from the showing in the drawings without departing-from the invention, and, in practice, several additional valves over those illustrated are usually employed, but for the purpose of illustration here, I have shown a simplified form of arrangement by which the method may be readily understood. No endeavor will be made to describe the specific piping as this is largely a matter of convenience, but will simply describe the five valves illustrated and explain their uses.

I isa vacuum valve, or the valve which controls the exhausting of air\ from the pressure pot. J is a vacuum relief valve, the function of which is to preclude the building up of too great a vacuum. K is a pressure valve or the valve by means of which pressure is admitted to the pressure pot. L is a check valve and M a vent valve. The check valve L and the vent valve M are included in the same branch of piping and together control the admission of air at atmospheric pressure into the system. In practice, the valves K and M are preferably manually operated, the valves I and L are preferably controlled by the position of the pot. while the valve J is automatically controlled by the degree of vacuum and is normally closed unless an excess vacuum is built up, whereupon it automatically opens and holds down the vacuum.

It ma be here noted that, in practice, the valves and M are coupled together, so that when the pressure pot is in casting position and pressure is turned into the pot,

through an opening in the valve K, the vent valve M will be closed, and, conversely, when the pressure is shut OK, the vent valve will be opened. These valves may be operated automatically, but 1 preferably operate them manually, so that there will be no liability of pressure being turned into the pot and the metal forced through the nozzle thereof until the operator of the machine has assured himself that the nozzle of the pot is in proper cooperative relation to the inlet of the die. In this way, accidents due to burning of the operator or broadcast distribution of molten metal are obviated. These several features are, however, optional and the valves of the piping system maybe operated either mechanically or automatically as desired.

I will now explain the operation of the apparatus shown in the carrying out of the method of this invention, explaining the several steps of the method and the various positions which the pressure pot and the several valves of the system partake during the operation of charging and discharging the pot.

Figure 1 shows the parts in the position which they take while the pot is being discharged, i. e. its contents being forced into the die. This is accomplished by the opening of the pressure valve K to admit pressure into the pot, while all the other valves in the system may be closed. The system should be sealed at this time, but as the vent valve is. closed to accomplish this, the check valve L may be opened. I

At the conclusion of the discharging operation, the pressure valve K is closed. and simultaneously,the vent valve M is opened, so that the pot is vented and the metal which remains therein assumes a quiescent state in 'thebase of the pot. The pot is now slid upon the guides G to the retracted position shown in Figure 2, at which time, the crank H engages with the member h and the pot proceeds to tilt. During the tilting of the pot from the position shown in Figure 2 to that shown in Figure 3, both the check valve L and the vent valve M will be open, while the vacuum valve I will be closed. The pot will be vented and will remain in this con- .dition until it reaches the position shown in the metal bath, thereby obviating the slightest tendency of the surface dross to flow into the pot during this initial tilting operation.

When the pot reaches the position shown in Figure 3, the check valve L will be closed, and the vacuum valve I opened with the result that air will be exhausted from the pot and molten metal will flow from the bath through the charging opening d into the pot. The pot will continue to tilt, until it assumes the position shown in Figure 4, during which time, the valves will remain the same as in Figure 3 and the charging operation of the pet will continue.

Figure 4 shows the pot tilted to the maximum and after reaching this maximum tilt, the pot will commence to right itself.

During the initial part of the righting operation, the charging of the pot may continue to assure that it is fully charged, but as the charging opening of the pot approaches the surface strata of the bath, and before it reaches the dross strata, the vacuum valve I is closed, and the check valve L is opened. The vent valve M has remained opened during the previous operations, so that at this time, the charging of the metal will cease and the venting of the pot will take place. This occurs when the pot is in approximately the position shown in Figure 5.

As soon as the pot is vented the .surplus metal which has been drawn into the pot through the charging operation, commences to flow out of the charging opening, and continues to flow, while the charging opening of the pot is passing through the surface dross strata of the bath and for a time thereafter,

as shown in Figure 6 until through continued tilting of the pot, it assumes its upright position shown in Figure 2 with the valves in the condition shown in Figure 2.

While these operations have been occurring, the die has been prepared for the next casting operation, so that the pot may now be moved forward into cooperative relation with the die and in position for the next casting operation. The vent valve M is then closed and the pressure valve K opened to admit pressure into the pot for the purpose of partially discharging the contents v of said pot through the forcing of the metal therein into the die. The parts of the apparatus are at this time, as shown in Fig ure 1, one complete operation of casting having been accomplished.

The series of operations described are repeated for each casting, and, in practice,'are

accomplished with more or less rapidity and in relatively continuous sequence.

It will be apparent from the foregoihg description that the entrance of surplus dross or impurities, which stratify on the surface of the molten metal b-ath, into the pressure pot, is entirely obviated. I have referred to the flowing of metal through the nozzle during the initial tilting of the" pot anolthis will occur if there is any appre ciable amount of metal left in the pot after the previous casting operation, but even though this does not occur, the surface metal. of the bath will not flow into the pot during this time, for the reasonthat the vacuum is not turned on until the nozzleis well below the surface of the bath. During the'righting of the pot, however, molten metalwill fiow from the nozzle during its passage through the surface strata of the-bath, so that when the pot is fully righted and ready for casting, it will be entirelyfree from surface impurities, dross or slag.

It will be manifest that applicants method is not limited to the completeor detailed operations hereinbefore described, but that the invention is as broad as is. commensurate with the appended claims. Moreover, the apparatus, described, both specifically and generically, forms part of applicants inven tion.

Having thus fully described the invention, what I claim as new and desire to secure by Letters Patent is:

1. In the art of die casting, the method of charging a casting pot which consists in'tilting the pot to bring its charging opening below the surface dross strata of a poolof molten metal, precluding the entrance of surface dross: into the pot during such tiltin movement, drawing metal into the pot so ely from below the surface dross strata, and then-righting the pot, and precluding the entranceof dross into the pot during the righting thereof. r

2. In the art of die casting, the method of charging a casting pot which consists in introducing its charging opening below the surface dross strata of a pool of molten metal while precluding the flow of dross into the pot, then drawing dross-free metal intothe pot by means of a vacuum, and thereafter removing the charging opening of the pot from the pool and precluding the entrance of dross into the pot while said outlet is passing through the surface dross strata.

3. In the art of die casting, the method of introducing molten metal into a tiltable pressure pot which consists in submerging the metal inlet to the pot below the surface of the bath of metal, then drawing metal intothe pot by means of a vacuum created therein, then tilting the pot so as toelevate the metal inlet to the pot above the surface of the metal bath but breaking the vacuum. in the pot before it reaches the superficial dross strata.

4:. In the art of die casting, the method of introducing molten metal ir to a tiltable pressure pot which consists in submerging the metal inlet to tlu pot below the surface of the bath of metal, then drawing metal into the pot by means of a vacuum created therein, then tilting the pot so as to elevate the metal inlet to the pot above'the surface of the metal bath but breaking the vacuum in the pot before it reaches the superficial dross strata, then utilizing a portion of the metal in the pot for casting, then again tilting the pot so that its metal inlet becomes submerged in the metal bath, but causing metal to flow out of saidinlet during its downward passalge through the dross strata on the bath, W ereby slag or dross is precluded from entering the pot.

5. In the art of die casting, the method of supplying mbiten metal to a tiltable casting pot, which consists in moving the pot to submerge its charging opening into a body of molten metal at a point therein below the surface dross strata of the body of molten metal, then producing a partial Vacuum in the pot so as to induce the flow of molten metal into the pot, thereafter returning the pot to initial position and breaking the partial vacuum in the pot before the charging inlet thereof reaches the surface dross strata of the molten metal body, whereby only pure metal enters the pot.

6. In the art of die casting, the method of sup-plying molten metal to a tiltable casting pot which consists in tilting the pot so that its metal inlet is submerged below the surface dross strata of a molten metal bath, precluding the charging of the pot until its inlet has passed below the surface dross strata of the bath, and producing a partial vacuum in the pot while its inlet is below the surface dross strata to effect a flow of dross=free metal into the pot, whereby the pot is charged with dross-free metal only.

7. In the art'of die casting, the method of supplying dross-free metal to a tiltable casting pot, which consists in tilting the pot to bring the charging opening thereof below the surface dross strata of a molten metal bath, effecting the flow of metal into the pot by means of a vacuum, while the charging opening thereof is below the surface dross strata, and causing a portion of the metal within the pot to flow from the charging.

vthe pot after its charging opening is passed below the surface dross strata of the molten metal bath to induce the flow of molten metal into the pot, maintaining the partial vacuum in the pot for a sufficient time to effect the charging of the pot above its normal casting capacity, then returning the pot to initial position and breaking the vacuum before the charging opening of the pot reaches the surface dross strata of the molten metal bath, whereby apart of the contents of the pot is pouring from the charging opening thereof during its upward passage through the surface dross strata of the bath for the purpose of precluding the entrance of surface dross into the pot.

In testimony whereof, I have signed my name to this specification.

CHARLES M. GREY. 

